This invention relates to a data storage system for a vehicle, and more particularly, the invention relates to a data storage system with a limited size primary storage device.
Heavy duty vehicle operators often use more than one vehicle. Additionally, it is common to track vehicle and driver information for the particular heavy duty vehicle for analysis by a fleet operations facility. Accordingly, it is desirable to utilize portable hand held computing devices, or personal digital assistants (PDA), that may be installed and removed from the vehicles to obtain and transfer data from the operator to the vehicle and vice versa. However, since the PDAs are portable they typically have relatively limited memory. Therefore, to ensure that no data is lost, it is desirable to preserve the data residing in the memory of the PDA.
Mass data storage systems have been used to troubleshoot or diagnose vehicle problems. These data storage systems have been controlled by a program that has been developed by an engineer or technician after a problem has been experienced in the vehicle. As a result, prior art data storage systems are not suitable for identifying and recording information relating to a problem as it occurs in the vehicle. Specifically, if a collision avoidance system on a heavy duty vehicle has been activated it is meaningless to go back at a later date with a program to identify or recreate the events that occurred to activate the collision avoidance system. The memory typically used in a vehicle is limited which is problematic for recording all the data that is available. Therefore, what is needed is a data storage system that can identify a problem and record data as it occurs and download the relevant data for analysis at a later date.
In one aspect of the present invention, a vehicle data storage system is provided which includes a plurality of sensors for sensing vehicle operating conditions, such as engine temperature. A control module receives the vehicle operating conditions and translates the vehicle operating conditions into vehicle information. That is, the raw electrical signals are translated into a code representative of particular values. A portable hand held computing device, such as a Handspring(copyright) or Palmpilot(copyright), has a data storage device or memory that receives the vehicle information. The data storage device is limited by a particular memory capacity. A secondary storage device receives the vehicle information from the PDA data storage device when the memory capacity reaches a desired memory capacity level, such as when there is only 10% of the memory left in the data storage device. Accordingly, the present invention retains data in the memory of the portable hand held computing device in a secondary storage device so that no data is lost.
In another aspect of the invention, a plurality of subsystem control modules, such as brake and engine control modules, translates the vehicle operating conditions into corresponding vehicle information. One of the vehicle operating conditions in one of the subsystem control modules comprises a triggering event. The triggering event may be detecting a high engine temperature in an engine temperature sensor. The subsystem control module then produces a request signal for event data in response to the triggering event. A memory buffer stores the vehicle information from all of the subsystem control modules. The event data is defined by a first predetermined time before the triggering event to a second predetermined time after the triggering event so that the data surrounding the triggering event resides in the memory buffer. The data in the memory buffer is written over by new data unless a request signal is received. A secondary storage device receives the event data in response to the request signal. Accordingly, data is stored in a secondary storage device when the triggering event occurs in the vehicle so that the data may be analyzed without the need for subsequently attempting to reproduce the vehicle problem.